Surgical tipping apparatus

ABSTRACT

An apparatus and method for ultrasonically forming a surgical suture tip from a length of unfinished surgical suture material. The apparatus includes a first tipping die having a first face for contacting a portion of the length of unfinished surgical suture material. A second tipping die having a second face is also provided. The first and second die also having extending therefrom a first member and a second member. The first and second dies cooperate with the first and second members to form a length of suture. At least one mechanical actuator is provided for moving the first face of the first tipping die and the third face of the first member toward the second face of the second tipping die and the fourth face of the second member. A second actuator vibrates at least one of the first and second tipping dies at an ultrasonic frequency of about 15 KHz to about 70 KHz. The method of ultrasonically forming a suture tip comprises the positioning a surgical suture between the first, second, third and fourth faces of the tipping apparatus then vibrating the dies at an appropriate frequency.

The present application is a continuation-in-part of Ser. No. 09/277,670that was filed on Mar. 26, 1999 now U.S. Pat. No. 6,035,916 (herebyincorporated by reference herein), which is a divisional of Ser. No.08/739,561 U.S. Pat. No. 5,891,166 that was filed Oct. 30, 1996 andissued on Apr. 6, 1999. The present invention is directed to systems forprocessing strings and yarns. More particularly, the present inventionis directed to surgical tipping apparatus for forming surgical suturetips through the use of ultrasonic welding.

FIELD OF THE INVENTION BACKGROUND OF THE INVENTION

Various automated systems for forming and cutting surgical suture tipsexist or are known in the art. In one such machine, means forsimultaneously advancing in parallel at least six separate strands ofsuture material, and six independent tensioners for maintainingrespective parallel portions of each of the six strands at a presettension are provided. Once a predetermined length of suture material hasbeen advanced by the advancing means, a horizontal heater bar(positioned perpendicular to the six suture strands) is actuated by anelectronically controlled solenoid which moves a planar heater bar intocontact with one side of the suture strands for a predetermined dwelltime. Once the predetermined dwell time has elapsed, the solenoidretracts the heater bar to its original position, and the heat exposed(or heat-stiffened) section of suture material is advanced to a cuttingstation. At the cutting station, the heat-stiffened section of suturematerial is cut at its midpoint, thereby producing a suture with twostiffened ends. Other mechanisms for forming and cutting surgical suturetips are shown in U.S. Pat. Nos. 4,832,025, 4,806,737 and 5,226,336 toCoates. The system described in the Coates patents uses convective ornon-contact heating to form suture tips.

Known systems for forming and cutting surgical suture tips suffer fromseveral drawbacks. First, such systems typically use heat to stiffen thesurgical suture tips. Since the unfinished surgical suture material usedby such systems is often coated, the heat applied during the tippingprocess may melt the coating. Once it has melted, the coating from theunfinished surgical suture material often adheres to the tippingmachine, thereby compromising the machine's performance. Anotherdrawback of known systems for forming and cutting surgical suture tipsis that such systems typically produce a suture tip, which lacks asubstantially uniform cross-section.

In addition, such systems are undesirable in that they typically cut thesuture tip in an imprecise manner, thereby leaving a cut end, which maybe irregular or distorted in shape. From a manufacturing standpoint,suture tips having non-uniform cross-sections and/or irregular ordistorted cut ends are undesirable because, among other things, suchsutures are difficult to insert into needles. Finally, known systems,which use heat to stiffen surgical suture tips are undesirable becausesuch systems cannot be used with sutures formed from silk.

It is therefore an object of the present invention to provide a systemfor forming surgical suture tips, which system does not use heat informing the suture tips and which may be used to fuse silk.

It is a further object of the present invention to provide a surgicalsuture having a welded core, which facilitates the easy insertion of thesuture tip into a needle.

It is a further object of the present invention to provide an automatedsystem and method for manufacturing surgical sutures having tips withwelded cores.

It is a still further object of the present invention to provide anautomated system and method for making surgical sutures with tips havingprecisely cut ends.

It is yet another object of the present invention to provide anapparatus for tipping sutures and method for making suture tips.

These and other objects and advantages of the invention will become morefully apparent from the description and claims, which follow or may belearned by the practice of the invention.

SUMMARY OF THE INVENTION

The present invention is directed to a multifilament surgical suturehaving a body portion and a tip portion, which is adjacent to the bodyportion. The surgical suture is formed of a plurality of filaments. Thetip portion has a tip length, a tip cross-section perpendicular to thetip length, and a tip core positioned at a center of the tipcross-section and along the tip length. The filaments positioned at thetip core are ultrasonically fused together.

In accordance with a further aspect, the present invention is directedto an apparatus for ultrasonically forming a surgical suture tip from alength of unfinished surgical suture material. The apparatus includes afirst tipping die having a first face for contacting a portion of thelength of unfinished surgical suture material. A second tipping diehaving a second face is also provided. At least one mechanical actuatoris provided for moving the first face of the first tipping die towardthe second face of the second tipping die. A second actuator vibrates atleast one of the first and second tipping dies at an ultrasonicfrequency of about 15 KHz to 70 KHz.

In accordance with a still further aspect, the present invention isdirected to a method for ultrasonically forming a surgical suture tipfrom a length of unfinished surgical suture material. The length ofunfinished surgical suture material is positioned at a location betweena first face of a first tipping die and a second face of a secondtipping die. After the positioning step, the surgical suture tip isformed by vibrating at least one of the first and second tipping dies atan ultrasonic frequency of about 15 KHz to 70 KHz.

In accordance with yet another aspect of the present invention there isprovided an apparatus for ultrasonically forming a surgical tip from alength of surgical suture material. The apparatus comprises a firstface, second face, third face, and fourth face. At least one mechanicalactuators is provided for moving a first face and third faces toward thesecond face and fourth faces of the tipping apparatus. At least one ofthe dies is operably linked to a source of ultrasonic vibration in afrequency in the range of from about 15 KHz to 70 KHz.

In accordance with yet another aspect of the present invention there isprovided a method for ultrasonically forming a surgical tip from alength of surgical suture material. A length of surgical suture materialis positioned at a location between a first face and third faces of afirst tipping die and a second face and fourth faces of a second tippingdie. After the surgical suture material is in place the dies arecontacted with the suture to shape the suture into the desired shape andat least one of the dies is vibrated at an ultrasonic frequency of about15 KHz to 70 KHz.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the manner in which the above-recited and other advantagesand objects of the invention are obtained and can be appreciated, a moreparticular description of the invention briefly described above will berendered by reference to a specific embodiment thereof which isillustrated in the appended drawings. Understanding that these drawingsdepict only a typical embodiment of the invention and are not thereforeto be considered limiting of its scope, the invention and the presentlyunderstood best mode thereof will be described and explained withadditional specificity and detail through the use of the accompanyingdrawings.

FIG. 1 is a schematic diagram showing a machine for ultrasonicallyforming and cutting surgical sutures, in accordance with a preferredembodiment of the present invention.

FIG. 2 is a side view of a suture tipping station formed from a pair ofopposing tipping dies one of which is in its retracted position, inaccordance with a preferred embodiment the present invention.

FIG. 3 is a side view of the suture tipping station of FIG. 2, whereinone of the tipping dies in the station is in its extended position.

FIG. 4 is an enlarged view of a portion of the suture tipping stationshown in FIG. 2.

FIG. 5 is an enlarged view of a portion of the suture tipping stationshown in FIG. 3.

FIG. 6 shows a cross-sectional view of a length of surgical suturematerial, which has been ultrasonically fused at its core, in accordancewith a preferred embodiment of the present invention.

FIGS. 7 and 8 show side views of opposing tipping dies forultrasonically forming surgical suture tips, in accordance withalternative preferred embodiments of the present invention.

FIG. 9 is a cross-sectional view of a moving clamp shown in its closedstate for grasping and advancing surgical suture material, in accordancewith a preferred embodiment of the present invention.

FIG. 10 is a cross-sectional view showing the moving clamp of FIG. 9 inits open state, in accordance with a preferred embodiment of the presentinvention.

FIG. 11 is a cross-sectional view of a stationary clamp shown in itsclosed state for grasping surgical suture material, in accordance with apreferred embodiment of the present invention.

FIG. 12 is a cross-sectional view showing the stationary clamp of FIG.11 in its open state, in accordance with a preferred embodiment of thepresent invention.

FIG. 13 is an isometric view of a system for tensioning a length ofsurgical suture material, in accordance with a preferred embodiment ofthe present invention.

FIG. 14 is an isometric view of an optical detection system fordetecting knots in surgical suture material passing through the system,in accordance with a preferred embodiment of the present invention.

FIG. 15 is a further isometric view showing a knot positioned betweenthe optical source and the optical detector of the knot detection systemof FIG. 14, in accordance with a preferred embodiment of the presentinvention.

FIG. 16 is a cross-sectional view of FIG. 15, showing a knot positionedbetween the optical source and the optical detector of the knotdetection system of FIG. 14, in accordance with a preferred embodimentof the present invention.

FIG. 17 is a side view of a suture tipping station formed of opposingcircular tipping dies, in accordance with an alternative preferredembodiment of the present invention.

FIG. 18 is a cross-sectional view of the suture tipping station shown inFIG. 17.

FIG. 19 is a side view of a suture tipping and cutting station formed ofopposing circular tipping and cutting dies, in accordance with a furtheralternative preferred embodiment of the present invention.

FIG. 20 is a cross-sectional view of a preferred embodiment of thesuture tipping station shown in FIGS. 4 and 5.

FIG. 21 is a cross-sectional view of an alternative set of dies to beused in the tipping station shown in FIGS. 4, 5, and 20.

FIG. 22 is a scanning electron micrograph of a cross-section of a tippedregion of a suture.

FIG. 23 is a scanning electron micrograph of a cross-section of anuntipped region of a suture.

DETAILED DESCRIPTION OF THE INVENTION

Overall System Operation

Referring now to FIG. 1, there is shown a schematic diagram showing amachine 10 for ultrasonically forming and cutting surgical sutures, inaccordance with a preferred embodiment of the present invention. Acontinuous length of unfinished surgical suture material 110 is suppliedto machine 10 from a supply spool 100 having unfinished surgical suturematerial 110 wound thereon. Unfinished surgical suture material 110 fromsupply spool 100 is initially advanced through a tensioning assembly 200for creating a tension in the unfinished surgical suture material, andthen through a knot detector system 300 for detecting whether a knot ispresent in any unfinished surgical suture material 110 passing throughknot detector system 300. After passing through the knot detector system300, the unfinished surgical suture material is advanced to a tippingstation 400, where a predetermined length of the unfinished surgicalsuture material 110 is ultrasonically formed into a length of surgicalsuture tip material. After the ultrasonically formed surgical suture tipmaterial is formed in station 400, the suture tip material is advancedto a cutting station 450 (e.g., an automated scissor or guillotinecutter) where the suture tip material is cut, thereby yielding afinished surgical suture having a body portion formed of unfinishedsurgical suture material 110 and an ultrasonically formed tip portionterminating with a cut end.

As explained more fully below, the unfinished surgical suture material110 from supply spool 100 is advanced through machine 10 by a movingclamp 500, which is coupled to a linear actuator 550 for driving themoving clamp 500 between a starting or home position 510 on one side ofthe cutting station 450 and an end position 512 on the other side of thecutting station 450. Moving clamp 500 has a grasping (or closed) stateshown in FIG. 9, and a non-grasping (or open) state shown in FIG. 10. Inaccordance with instructions received from a controller 800, the movingclamp 500 selectively grasps and pulls the unfinished surgical suturematerial 110 through machine 10 in order to facilitate the manufactureof the finished surgical sutures. In addition to advancing unfinishedsurgical suture material through the machine, the moving clamp 500functions to initially position and align the unfinished surgical suturematerial 110 within the tipping station 400.

During operation of the machine 10, the moving clamp 500 initiallygrasps or closes on the unfinished surgical suture material 110 at thehome position 510. Next, while the moving clamp 500 remains in itsgrasping or closed state, the linear actuator 550 drives the movingclamp 500 from its home position 510 to the end position 512. As thelinear actuator 550 drives moving clamp 500 from its home position 510to its position 512, the moving clamp 500 pulls a length of theunfinished surgical suture material 110 through the station 400 andthrough a stationary clamp 600 positioned adjacent to the end position512. Like the moving clamp 500, the stationary clamp 600 has a grasping(or closed) state, which is shown in FIG. 11, and a non-grasping (oropen) state shown in FIG. 12. As the linear actuator 550 drives themoving clamp 500 from home position 510 to end position 512, thestationary clamp 600 is in its open state. After the moving clampreaches its end position 512, the stationary clamp 600 grasps or closeson the unfinished surgical suture material 110 positioned within thestationary clamp 600. The positions of cutting station 450 andstationary clamp 600 along the length of machine 10 may be adjusted inorder to facilitate the creation of sutures with different lengths.

As illustrated in FIGS. 2-3, the combined tipping and cutting station400 includes a pair of opposing tipping dies 402, 404. The tipping die402 has both an open state (shown in FIG. 2) and a closed state (shownin FIG. 3). When, as described above, the linear actuator 550 drives themoving clamp 500 from home position 510 to end position 512, the tippingdie 402 in station 400 is in its open position. After the moving clampreaches its end position 512 and the stationary clamp 600 has grasped orclosed on the unfinished surgical suture material 110 positioned withinthe stationary clamp 600, the tipping die 402 moves from its open (orretracted) state to its closed (or extended) state in order tofacilitate the ultrasonic forming of a predetermined length of surgicalsuture tip material. As described in greater detail below in connectionwith FIGS. 2-5, while the tipping die 402 is in its closed state, atleast one of the tipping dies 402, 404 vibrates at an ultrasonicfrequency in order to form a length of surgical suture tip material.After the tipping die 402 has been in its closed state for apredetermined period of dwell time (i.e., weld time plus hold time),tipping die 402 moves from its closed to its open state, therebyyielding a length of tipped surgical suture material positioned betweendies 402, 404. While this length of tipped surgical suture materialremains positioned between dies 402, 404, a further length of tippedsurgical suture material (previously tipped by station 400) which ispositioned within cutting station 450 is severed by station 450, therebyyielding a tipped surgical suture with a cut end.

While the surgical suture material positioned at station 400 is beingtipped, the moving clamp 500 opens and releases the surgical suturematerial within its grasp and, with the tipping die 402 still in itsclosed state, the linear actuator 550 drives the moving clamp 500 fromits end position 512 to its home position 510 where the moving clampcloses on a next piece of unfinished surgical suture material 110. Next,after the tipping of the surgical suture material at station 400 iscompleted and the tipping die 402 is in its open state, the suturematerial at station 450 is cut. Thereafter, the stationary clamp 600releases the surgical suture material within its grasp (i.e., a finishedsurgical suture with a cut tip), the linear actuator 550 drives theclosed moving clamp back to its end position 512, and the processdescribed above is then preferably repeated in order to manufacturefurther finished surgical sutures. Since the tensioning assembly 200exerts a tensioning force on the surgical suture material 110 positionedwithin machine 10, it is important for the moving clamp 500 to grasp orclose on the surgical suture material prior to the time that thestationary clamp 600 opens, in order to prevent the tensioning assembly200 from pulling the trailing end of the surgical suture material cut bystation 450 in a reverse direction when the tipped surgical suturematerial is severed by station 450.

The unfinished surgical suture material 110 used in machine 10 formanufacturing the finished sutures may consist of any thermoplasticbraided suture material such as, for example, a polyester braided suturematerial, or a polyamide or polyolyfin suture material. In addition, theunfinished surgical suture material 110 used in machine 10 may consistof silk or linen material, in which case, machine 10 may be used toultrasonically fuse silk or linen tips. Alternatively, the unfinishedsurgical suture material 110 used in machine 10 may consist of nylonmaterial, in which case, machine 10 may be used to ultrasonically fusenylon tips. In a preferred embodiment of the present invention describedmore fully below, the unfinished surgical suture material 110 used inmachine 10 is a braided suture material formed of a polyethyleneterephthalate, such as that sold by Ethicon, Inc. under the trademarkETHIBOND® EXCEL®. In a preferred embodiment, a Simatic Model TI1435controller manufactured by Siemens is used to implement controller 800.An operator interface is preferably coupled to the controller 800.

Operation of Tipping Dies

As mentioned above, after the moving clamp 500 has reached its endposition 512, the tipping dies 402, 404 in the tipping station 400operate to ultrasonically form a predetermined length of surgical suturetip material from the unfinished surgical suture material 110 positionedwithin the station 400. During the operation of the tipping dies 402,404, the unfinished surgical suture material 110 is suspended in analigned and fixed positioned within station 400 by the stationary clamp600, which is positioned on one side of station 400, and by the pulley514, which is positioned on an opposing side of station 400. Inaddition, during the operation of the tipping dies 402, 404, theunfinished surgical suture material 110 suspended within station 400 ismaintained at a preset tension by tensioning system 200.

FIGS. 2 and 3 show two views of the tipping station 400. Each of theviews illustrates the position of the tipping dies 402, 404 at aparticular point during a suture tipping cycle. Referring nowspecifically to FIG. 2, there is shown a side view of station 400,wherein the tipping die 402 is in its retracted or open position. FIG. 2shows the position of tipping die 402 when the moving clamp 500 firstreaches its end position 512. After the moving clamp 500 has reached itsend position 512, a cylinder 406 (controlled by controller 800) drivesthe tipping die 402 from its retracted to its extended position. Inmoving the tipping die 402 between its retracted and extended positions,cylinder 406 drives tipping die 402 along the axis indicated by arrows408. FIG. 3 shows the position of the tipping die 402 after the cylinder406 has moved tipping die 402 to its extended position. As the tippingdie 402 is moved to its extended position, a cross-sectional portion ofthe suture material 110 suspended within station 400 is contacted byface 402a of tipping die 402 and face 404a of tipping die 404. In oneembodiment of the present invention, the cylinder 406 causes tipping diefaces 402a and 404a to apply pressure to (or squeeze) the outer surfacesof the suture material 110 positioned between dies 402 and 404. In thisembodiment, about 25 PSI of pressure is applied to the outer surfaces ofthe suture material when die faces 402a and 404a "close-on" or squeezethe suture material positioned in station 400.

The first tipping die 402 and second tipping die 404 in a preferredembodiment (illustrated in FIG. 20) will have extending from the faces402a and 404a a first member and second member 420 and 422 respectively.The first and second members 420 and 422 provide a third and fourth diefaces 420a and 422a for the tipping system to complete the forming ofthe suture tip during the tipping operation. The first member 420 andthe second member 422 will contact the opposite tipping die surface fromwhich they extend to completely capture the suture within the dies. Thefirst and second members 420 and 422 will preferably be biased to exertpressure against the opposite die face to which they extend to preventthe suture from extruding from the dies when they are closed. The firstand second members (420, 422) as illustrated in FIG. 20 may be attachedto a plungers 434 and 436 (respectively), which will move from anextended position to a closed position within chamber 452 and 451(respectively). The member 420 and 422 are preferably biased in anextended position by mechanical means (such as provided by springs 430and 428, respectively) and/or fluid pressure (such as provided via fluidconduits 424 and 426, respectively). The closing of the dies 402 and 404generally along the axis 453 forces the members into a closed position.As the dies 402 and 404 are closed the first, second, third, and fourthdie faces 402a, 420a, 404a and 422a of the members will contact thesuture (preferably simultaneously) and provide a shape to the sutureduring the ultrasonic tipping process. The die faces 402a and 404a (ofthe first and second dies) and die faces 420a and 422a (first and secondmembers) may be modified to provide the desired shape to the sutureafter the dies have closed. As is illustrated in FIG. 21 the first andsecond die faces and the third and fourth die faces respectively 402,404, 420, and 422 may have a recess 402c, 404c, 420c, and 422c to shapethe suture after the dies have closed into a circular cross-section.

After faces 402a and 404a (and optionally 420a and 422a) have beenbrought together and the tipping dies 402, 404 (and optionally 420 and422) have "closed on" the unfinished surgical suture material 110 asshown in FIG. 3, one or both of the tipping dies 402, 404 (andoptionally 420 and 422) vibrate at an ultrasonic frequency for apredetermined weld time in order to form a suture tip. In the preferredembodiment, tipping die 402 remains fixed in position during a dwelltime (i.e., a weld time followed by a hold time) when the tipping dies402, 404 (and optionally 420 and 422) have closed-on the unfinishedsurgical suture material 110, and an ultrasonic horn 412, which isconnected to tipping die 404 vibrates tipping die 404 along the axis 410at a frequency of 15 KHz to 70 KHz and an amplitude of 0.0001 to 0.010inches for about 0.050 to 10.0 seconds in order to form the suture tip.In a preferred embodiment of the present invention the horn 412 will beincorporated within tipping die 404. In a still further preferredembodiment, horn 412 vibrates tipping die 404 at a frequency of about 15KHz to about 40 KHz at an amplitude of 0.004 inches for 200 ms duringthe suture tipping step. During the dwell time when the tipping dies402, 404 (and optionally 420 and 422) have closed-on the unfinishedsurgical suture material 110, the vibrating of tipping die 404 (andoptionally 420) against tipping die 402 (and optionally 422) primarilycauses filaments within the interior or core 112 (shown in FIG. 6) ofthe unfinished surgical suture material 110 (and to a lesser extentfilaments on the exterior surface 114 of the suture material) to fuse orweld together, thereby forming a length of surgical suture tip materialbetween dies 402, 404 (and optionally 420 and 422). Thereafter, at theend of the dwell time, the cylinder 406 opens the tipping die 402 bybringing it back to its initial retracted position. In the preferredembodiment, a transducer 414, which is coupled to horn 412 by a booster416 is used for vibrating horn 412. Booster 416 functions to control theamplitude of the ultrasonic vibrations. A finished surgical sutureformed with an ultrasonically fused suture tip as described above hasbeen found to exhibit a tensile strength along the suture tip that isabout 75% to 84% of the tensile strength of the body portion (i.e., theuntipped portion) of the finished suture.

The tipping parameters used to form an ultrasonically fused tip varydepending upon the diameter of the unfinished suture material 110 beingsupplied to machine 10. Set forth in Table I below are the preferredtipping parameters used for ultrasonically forming tips on differentsizes of an unfinished braided suture material formed of a polyethyleneterephthalate, such as that sold by Ethicon, Inc. under the trademarkETHIBOND® EXCEL®. Also set forth in Table I below for each size sutureis the preferred pressure to be applied by a 3 inch diameter drivercylinder to the exterior surfaces of a one inch length of suturematerial by tipping dies 402, 404 (and optionally 420 and 422) when thetipping dies first "close-on" the unfinished suture material, thepreferred frequency that tipping die 404 should vibrate during theultrasonic tipping process, and the preferred dwell times during whichthe tipping dies 402, 404 (and optionally 420 and 422) should remainclosed on (and vibrate against) the unfinished suture material 110during the ultrasonic tipping process.

                  TABLE 1                                                         ______________________________________                                        SIZE     0       2/0       3/0   4/0     5/0                                  ______________________________________                                        Tipping Die                                                                            80      25        25    15      5                                      Pressure                                                                      (in PSI)                                                                      Tipping Die 15-70 15-70 15-70 15-70 15-70                                     Vibration                                                                     Frequency                                                                     (in kHz)                                                                      Tipping Die 0.900- 0.400- 0.100- 0.025- 0.025-                                Weld Time 10.0 5.0 5.0 2.0 2.0                                                (in seconds)                                                                  Tipping Die 0.100- 0.100- 0.100- 0.100- 0.100-                                Hold Time 0.500 0.500 0.500 0.500 0.500                                       (in seconds)                                                                ______________________________________                                    

In the preferred embodiment of the present invention, tipping dies 402,404 (and optionally 420 and 422) are made of steel, and are coated witha non-stick substance such as tin, TEFLON® or NEDOX®, in order tofacilitate the release of the suture material from the tipping dies 402,404 (and optionally 420 and 422) when such dies are opened. Although inthe preferred embodiment described above, the tipping dies 402 and 404(and optionally 420 and 422) were a particular shape, it will beunderstood by those skilled in the art that tipping dies defining othershapes, such as those shown in FIGS. 7 and 8, may also be used toultrasonically form suture tips in accordance with the presentinvention. Similarly, although the ultrasonically tipped suture shown inFIG. 6 has a circular cross-section, it will be understood by thoseskilled in the art that ultrasonically tipped sutures havingcross-sections of other shapes (e.g., polygonal) may be formed inaccordance with the present invention by varying the shape andorientation of the tipping dies employed. This apparatus can also beused to weld one or more sutures together (such as to form loops and thelike).

FIG. 22 is a scanning electron micrograph of a cross-section of a suturethat has been tipped using the inventive tipping equipment and process.For comparison purposes FIG. 23 illustrates an untipped region ofsuture. As can be seen from examining micrograph of the tipped suturethe present tipping device results in a tip that can consolidate thesuture fibers. The ultrasonically tipped sutures unlike heat tippedsutures do not transfer heat through the external surface of the suture.Consequently ultrasonically tipped sutures generally have differentsurface characteristics. The external surface of heat tipped sutureswill generally have melted and fused filaments and may become glassy. Aglassy suture surface is disadvantageous because when the suture isinserted into a needle and swaged the outer surface of the suture willbe embrittled and can cause a weaker linkage between the suture andneedle. As can be seen from FIG. 22 the external surface of theultrasonically tipped suture does not become glassy under normalcircumstances and individual filaments are still identifiable around theparameter (external surface) of the suture, which would be expected toprovide a stronger linkage between the suture and needle during swaging.Additionally as is illustrated by FIG. 22 the center of the suture maybe substantially consolidated into a unitary structure withsubstantially no voids. The unitary center of sutures that areultrasonically tipped and uniformly shaped under pressure allows formore consistent pullout values after the swaging of a needle onto thesuture.

Suture Tensioning System

Referring now to FIG. 13, there is shown an isometric view of the system200 for tensioning a length of surgical suture material 110, inaccordance with a preferred embodiment of the present invention. System200 includes a tensioning spool 202 having a width, a weight and acircular perimeter 204 perpendicular to the width of the spool. Thetensioning spool 202 has a groove 206 in its perimeter 204 for receivingthe surgical suture material 110. Tensioning system 200 also includes atrack 208 formed from a pair slots 208a, 208b extending in parallelalong the length of the track 208. Track 208 and slots 208a, 208b arepreferably positioned along a purely vertical axis, although, inalternate embodiments (not shown), track 208 and slots 208a, 208b may bealigned along an axis that includes both horizontal and verticalcomponents. The slots 208a, 208b function to receive and guide thetensioning spool 202 along the length of track 208 during operation ofsystem 200. The length of the track 208 is preferably alignedperpendicularly to the width of the tensioning spool 202.

During operation of the system 200, the tensioning spool 202 issuspended vertically within slots 208a, 208b by the surgical suturematerial 110. While the tensioning spool 202 is suspended verticallywithin slots 208a, 208b by the surgical suture material 110, the weightof the tensioning spool 202 exerts a corresponding tensioning force onthe suture material 110 equal to the weight of spool 202. In order tovary the tension exerted on the suture material 110 during operation ofsystem 200, additional weights 210 may be added or removed from a spoolarm extending from the center of spool 202. The tension exerted on thesuture material 110 during operation of system 200 preferably representsthe minimum tension necessary to prevent the suture material 110 fromgetting "bunched-up" as it is pulled through machine 10 by moving clamp500.

When the moving clamp 500 described above is in its grasping state andmoves from its home position 510 to its end position 512, suturematerial 110 suspended in the slots 208a, 208b is drawn forwardlythrough station 400 of machine 10. As the suture material is drawnforwardly through the machine by the moving clamp 500, the tensioningspool 202 is pulled upwardly within slots 208a, 208b. However,regardless of the vertical position of the spool 202 within the slots208a, 208b, the tension exerted on the suture material 110 by system 200will be the constant and equal to the weight of spool 202. An opticalsensor 212, coupled to controller 800, is provided for determiningwhether the pulling action of the moving clamp 500 has caused the spool202 to be drawn upwardly within the track 208 past the height of thesensor 212. When optical sensor 212 detects that the tensioning spool202 has been pulled upwardly past the location of the sensor 212,controller 800 causes a motor (not shown) coupled to the supply spool100 to unwind unfinished surgical suture material 110 from the supplyspool 100. As further unfinished surgical suture material 110 is unwoundfrom the supply spool 100, the tensioning spool 202 moves downwardlywithin the track 208. In the preferred embodiment, controller 800continues to unwind unfinished surgical suture material 110 from thesupply spool 100 until the tensioning spool 202 falls below the level ofoptical sensor 212. An optical sensor 214 is provided at the bottom oftrack 208 for determining whether there has been a break in the surgicalsuture material 110 or a loss of tension in the suture material withinmachine 10. Since, during normal operation, the tensioning spool 202should not fall below the level of optical sensor 212, a break in suturematerial 110 or a loss of suture tension within machine 10 will besignaled by sensor 214 if the sensor determines that the tensioningspool 202 has fallen to the level of the sensor 214.

Knot Detection System

Referring now to FIGS. 14 and 15, there are shown two isometric views ofan optical detection system 300 for detecting knots in surgical suturematerial 110 passing through system 300, in accordance with a preferredembodiment of the present invention. Knot detector system 300 includesan optical light source 302 for directing a plane of light 304 at anoptical light detector 306 when surgical suture material 110 ispositioned between the optical light source 302 and the optical lightdetector 306. The optical light source 302 is preferably formed of aplurality of optical fibers 302a having their terminating ends alignedalong the optical plane 304. Controller 800 is coupled to an output ofthe optical light detector 306 for processing the signals output bydetector 306 and determining whether a knot exists in the suturematerial 110 positioned between the light source 302 and light detector306. More particularly, by comparing a magnitude of a shadow 308 cast onthe optical light detector 306 by the suture material 110 against apredetermined threshold, controller 800 determines whether or not a knotexists in the suture material 110 positioned between the light source302 and light detector 306. In a preferred embodiment, the predeterminedthreshold used in this comparison corresponds to a magnitude of a shadow308a cast on the optical light detector 306 by an unknottedcross-section of suture material 110. In a still further preferredembodiment, controller 800 will determine that a knot exists in thesuture material 110 passing through system 300 only if the magnitude ofthe shadow cast on light detector 306 by suture material 110 exceeds byat least 30% the magnitude of a shadow 308a cast on the optical lightdetector 306 by an unknotted cross-section of suture material 110.

Extended Length Suture Mode

Although, in the process described above, machine 10 was used tomanufacture a finished surgical suture having a length that was lessthan length of the linear actuator 550, machine 10 may also be used inan extended length suture mode, described below, in order to makefinished surgical sutures, which are longer than linear actuator 550.During operation of the machine 10 in the extended length suture mode,the moving clamp 500 initially grasps or closes on the unfinishedsurgical suture material 110 at the home position 510. Next, while themoving clamp 500 remains in its grasping or closed state, the linearactuator 550 drives the moving clamp 500 from its home position 510 tothe end position 512. As the linear actuator 550 drives moving clamp 500from its home position 510 to its position 512, the moving clamp 500pulls a length of the unfinished surgical suture material 110 throughthe tipping station 400, cutting station 450 and through the stationaryclamp 600. After the moving clamp reaches its end position 512, thestationary clamp 600 grasps or closes on the unfinished surgical suturematerial 110 positioned within the stationary clamp 600. The movingclamp 500 then releases the unfinished surgical suture material 110 inits grasp. Next, while the moving clamp is in its open or non-graspingstate, the linear actuator 550 drives the moving clamp 500 from its endposition 512 to its home position 510, where the moving clamp 500 againgrasps or closes on the unfinished surgical suture material 110 at thehome position 510. After the moving clamp 500 grasps the unfinishedsurgical suture material 110 at the home position 510 for the secondtime, the stationary clamp 600 opens. Thereafter, while the moving clamp500 remains in its grasping or closed state and the stationary clamp 600remains in its open state, the linear actuator 550 again drives themoving clamp 500 from its home position 510 to the end position 512.After the moving clamp 500 reaches its end position 512 for the secondtime, the stationary clamp 600 again grasps or closes on the unfinishedsurgical suture material 110 positioned within the stationary clamp 600.

After the unfinished surgical suture material 110 has been "pulledtwice" by the moving clamp 500 as described in the paragraph above, thedies 402, 404 (and optionally 420 and 422) in the tipping station 400function as described above to ultrasonically form a length of surgicalsuture tip material positioned within the station 400. Following thecutting of this suture tip material at station 450, the stationary clamp600 releases the surgical suture material within its grasp. As thestationary clamp opens and releases the previously grasped surgicalsuture material, a finished surgical suture having an ultrasonicallyformed and cut tip results. Since the moving clamp 500 pulled the suturematerial 110 two times consecutively before the tipping station 400formed the suture tip, the resulting finished surgical suture producedby the extended length suture mode may have a length which is greaterthan the length of the linear actuator 550.

Continuous Process Using Circular Tipping Dies

Referring now to FIGS. 17 and 18, there are shown side andcross-sectional views of an alternative suture tipping station 400aformed of opposing circular tipping dies 440, 450 for continuouslytipping unfinished surgical suture material 110a, in accordance with analternative preferred embodiment of the present invention. Tipping die440 contains a notch 403 around a portion of its perimeter, and tippingdie 450 contains a corresponding groove 405 positioned about itsperimeter. In the preferred embodiment of station 400a, notch 403 issized such that pressure is applied to the exterior surface of suturematerial 110a when suture material 110a is between notch 403 and thelower end of groove 405. Tipping dies 440, 450 are coupled to mechanicalactuators (not shown) which continually rotate the dies 440, 450 in thedirection of the arrows shown in FIG. 17. During rotation of the tippingdies 440, 450, an ultrasonic horn (also not shown) vibrates tipping die440 against tipping die 450 at a frequency of about 15 KHz to about 70KHz (and preferably about 15 KHz to about 40 KHz) and an amplitude of0.0001 to 0.010 inches in order to continuously form suture tipmaterial. Station 400a may be substituted for station 400 in FIG. 1, inorder to configure machine 10 to continuously produce surgical sutureswith ultrasonically formed tips, in accordance with the presentinvention.

Referring now to FIG. 19, there is shown a side view of a suture tippingand cutting station 400b formed of opposing circular tipping and cuttingdies 440a, 450 for continuously tipping and cutting unfinished surgicalsuture material 110, in accordance with a further alternative preferredembodiment of the present invention. Die 440a is substantially the sameas die 440, except that die 440a includes a cutting point 403b forcutting a suture tip end portion during the rotation of die 440a against450. Station 400b functions substantially the same as station 400a,except that station 400b may be used to both form and cut suture tips ina continuous manner. Since the cutting performed by station 400b isaccomplished using a cutting point 403b, which vibrates at an ultrasonicfrequency, a suture tip is simultaneously both cut and sealed by station400b. In addition, the ultrasonic cutting action of point 403b yields acut suture tip with a lead angle, which facilitates the insertion of thecut suture tip into a drilled needle. Although in the preferredembodiment of station 400b, dies 440a and 450 function to both tip andcut surgical suture material 110, it will be understood by those skilledin the art that two separate pairs of circular dies may be employed inseries to respectively perform the tipping and cutting operations.

Furthermore, it is to be understood that although the present inventionhas been described with reference to a preferred embodiment, variousmodifications, known to those skilled in the art, may be made to thestructures and process steps presented herein without departing from theinvention as recited in the several claims appended hereto.

I claim:
 1. An apparatus for ultrasonically tipping a surgical suturecomprising:(A) a tipping apparatus having a first tipping die having afirst face for contacting a portion of said length of said unfinishedsurgical suture material; (B) second tipping die having a second facefor contacting a portion of said length of said unfinished surgicalsuture material; (C) a first member extending from said first tippingdie toward said second die having a third face for contacting a portionof said length of said unfinished surgical suture material; (D) a secondmember extending from said second tipping die toward said first diehaving a fourth face for contacting a portion of said length of saidunfinished surgical suture material; and (E) additionally present is atleast one mechanical actuator for moving said first face of said firsttipping die toward said second face of said second tipping die whereinsaid first, second, third and fourth tipping die faces contact and applypressure to the outer surface of the unfinished suture material; and asecond actuator for vibrating at least one of said first and secondtipping dies at an ultrasonic frequency of about 15 kHz to about 70 kHz.2. The apparatus of claim 1 wherein the first and second members havebiasing means.
 3. The apparatus of claim 1, wherein said second actuatoris provided for vibrating at least one of said first and second tippingdies at an amplitude of 0.0001 to 0.010 inches.
 4. The apparatus ofclaim 3, wherein said second actuator is coupled to said second tippingdie and forms an acoustic horn.
 5. The apparatus of claim 1, whereinsaid at least one mechanical actuator is formed from a cylinder coupledto said first tipping die for moving said first tipping die toward saidsecond tipping die.
 6. The apparatus of claim 1 wherein additionallypresent is(F) a cutting station for cutting said portion of saidsurgical suture; (G) a moving clamp for advancing the surgical suturematerial from the tipping station to the cutting station; and (H) astationary clamp for holding the suture in a stationary position,located adjacent to the cutting station.
 7. The apparatus of claim 1wherein the die faces are configured to provide a circular cross-sectionwhen the die faces are in a closed position.